以木质素磺酸钠(LS)为原料,聚乙烯醇为黏合剂,制备了木质素磺酸钠荧光膜.通过荧光光谱仪和激光粒度分析仪对LS的形态和光学性质进行了分析,研究了硝基化合物和无硝基化合物对LS的荧光猝灭作用及猝灭机理,并将木质素磺酸钠荧光膜应用于硝基爆炸物的检测.研究结果表明:LS随着制备溶剂中乙醇体积分数的增加,其荧光发射峰强度增加,分子之间发生缓慢聚集,且聚集体颗粒变大,具有聚集诱导发射(AIE)性质;硝基苯和对硝基苯酚均对LS的荧光猝灭程度高达90％,间二硝基苯对LS的荧光猝灭程度也有56％;苯、甲苯、苯酚、对苯二甲酸、对苯二甲醛和邻苯二甲醛等无硝基化合物对LS的荧光猝灭作用几乎没有.LS对硝基苯、间二硝基苯和对硝基苯酚等硝基化合物显示出专一、特异的高灵敏检测性能,该现象主要由光诱导电子转移机制造成的.浸泡过硝基苯/乙醇溶液、间二硝基苯/乙醇溶液和对硝基苯酚/乙醇溶液的木质素磺酸钠荧光膜的荧光猝灭程度分别为89％、78％和100％.将硝基化合物溶液在荧光膜上涂写,在日光下观察不到笔迹存在,而在紫外光下能观察到笔迹部分有明显的荧光猝灭现象.

Lignin is a significant byproduct from the pulp and paper industry. However, the conversion of lignin to a resource with added value is plagued by expensive processing. Here we report that the syringyl units (S) of sodium lignosulfonate (LS) exhibit phosphorescence in water with a lifetime of similar to 2 ms and the lifetime can be prolonged up to similar to 618 ms by encapsulation in Ca-3(PO4)(2) due to the formation of H-type dimers of the S units (LS@Ca-3(PO4)(2)). Motivated by this, we develop afterglow paper through the in situ generation of LS@Ca-3(PO4)(2) in the paper matrix. The afterglow emission of the paper is sensitive to H2O2, enabling its application as a sensor for liquid/vapor H2O2. Moreover, the afterglow paper is shown to be suitable for use in anti-counterfeiting applications, enabling the development of a more sustainable pulp and paper industry.

As the basic material of 3D printing, the binder is the key factor to a successful 3D printing process as it determines the property and structure of the printed bone scaffolds, as well as the reliability of the entire printing system. In this study, three commonly used polymeric binders (PVA, PVP and PAM) were applied to fabricate HA embryonic scaffolds by powder-based 3D printing technology. The suitable printing concentrations of three binders were screened by investigating their printability and drop penetration. Following, based on the printable binders, different scaffold samples were fabricated and characterized. And the effects of different binders on the properties of scaffolds were investigated in terms of mechanical properties and cell attachment. Results show that the binder of 1.0 wt% PVA and its scaffolds possess the best the printing resolution, solidification ability and compressive strength, while the binder of 1.5 wt% PVP and its scaffolds possess the shortest penetration time and the largest compressive modulus. Additionally, the cell culture experimental results demonstrate that the scaffolds printed with 1.0 wt% PVA process the best cytocompatibility and are most conducive to cell attachment among three binders. Therefore, comprehensive considering the current results of three binders we conclude that among three binders the binder of 1.0 wt% PVA is most suitable for fabricating HA bone scaffolds by 3D printing technology.

Natural phenolic compound–iron complexes were used as sustainable solar absorbers for wood-based solar steam generation devices.

笔者研究了胶水选用及粉材组分对三维打印羟基磷灰石/磷酸三钙(HA/β-TCP)骨支架性能的影响.为了改善骨支架的力学性能和生物兼容性,分别选用磷酸和聚乙烯醇作为黏结剂,使用Zprinter 250三维打印机制备了不同HA/β-TCP质量配比(100:0、80:20、60:40及40:60)的骨支架.通过孔隙率测量、吸水性实验、抗压强度试验、电镜扫描及细胞培养等多种实验方法,分别从连通性、微观结构、表面特性、力学性能及生物兼容性等方面分析了不同胶水及组分比例制备的骨支架性能.结果表明:使用磷酸作为黏结剂的骨支架,不论从微观结构还是生物兼容性和力学强度,其性能均优于聚乙烯醇制备的骨支架.当粉材中HA与β-TCP的比为60:40时,磷酸骨支架抗压强度取得最大值(4.8 MPa),此时其弹性模量为200 MPa,此外,细胞培养实验表明HA与β-TCP的比为60:40的磷酸骨支架在促细胞增殖生长方面的表现也最优.因此,后续的临床试验中可选用磷酸作为黏结剂,而HA与β-TCP比为60:40的骨支架更能促进细胞的生长和增殖.

During the process of bone scaffold manufacturing with 3D printing technology,the properties of binder is a key factor that affects the quality of bone scaffold.In this paper,a molecular dynamics simulation method was applied to build and simulate the models of three commonly used polymer binders,and some properties of polymer binders PVP,PAM and PVP are investigated from a microscopic molecular level,such as density,cohesive energy and mechanical properties.The performance parameters of three binders are compared and studied,and then the internal relations are also revealed.Moreover,the interaction models of binders and HA surfaces are constructed,and the interfacial bonding energies are calculated and compared respectively,and the root reason affecting polymer bonding properties is also found.This work not only predicts the basic properties of commonly used binder,but also provides the theoretical basis for the choice of binder for the bone scaffold manufacturing by 3D printing technology.

Based on plane strain hypothesis, radial displacement formula of polarized piezo ceramic cylinder excited by radial electric fieldwas derived. Radial polarized piezo ceramic cylinder, which is actuator of squeeze-mode piezoelectric inkjet printhead, perform mainly radial deformation under radial external electric field. Finite element (FE) simulationwas also carried out using the software of ANSYS 14.0. Inner surface radial displacements of different piezo tubeswere analyzed using the two methodsat 100 V. The difference between results of the analytic formula and FE simulation is less than 5%. Consistent results of two different methods verify qualification of the derived formula. The analytic model could be used to predict the response of squeeze-mode inkjet printer under external electric field, reduce design costs and improve design reliability and efficiency.

The objectives of this study were to develop a computational model based on molecular dynamics technique to investigate the compatibility and mechanical properties of Polyacrylamide (PAM)/Polyvinyl alcohol (PVA) blends. Five simulation models of PAM/PVA with different composition ratios (4/0, 3/1, 2/2, 1/3, 0/4) were constructed and simulated by using molecular dynamics (MD) simulation. The interaction mechanisms of molecular chains in PAM/PVA blend system were elaborated from the aspects of the compatibility, mechanical properties, binding energy and pair correlation function, respectively. The computed values of solubility parameters for PAM and PVA indicate PAM has a good miscibility with PVA. The results of the static mechanical analysis, based on the equilibrium structures of blends with differing component ratios, shows us that the elastic coefficient, engineering modulus, and ductility are increased with the addition of PVA content, which is 4/0 PAM/PVA<3/1 PAM/PVA<2/2 PAM/PVA<1/3 PAM/PVA<0/4 PAM/PVA. Moreover, binding energy results indicate that a stronger interaction exists among PVA molecular chains comparing with PAM molecular chains, which is why the mechanical properties of blend system increasing with the addition of PVA content. Finally, the results of pair correlation functions (PCFs) between polar functional groups and its surrounding hydrogen atoms, indicated they interact with each other mainly by hydrogen bonds, and the strength of three types of polar functional groups has the order of O(-OH)>O(-C=O)>N(-NH2). This further elaborates the root reason why the mechanical properties of blend system increase with the addition of PVA content.

A molecular dynamics simulation is employed to investigate the effects of nano-SiO2 particles on the properties of polyvinyl alcohol (PVA)/poly(vinyl pyrrolidone) (PVP) blends and demonstrate the interaction mechanism of nano-SiO2 particles in blend systems. Six blend systems with different concentrations of SiO2 particles (0–12.8%) and two interfacial interaction models of polymers on the SiO2 surface were designed and analyzed in terms of density distribution, mechanical properties, fractional free volume, and X-ray diffraction patterns. The incorporation of nano-SiO2 particles into the PVA/PVP blend systems increased their mechanical properties, densities, and semicrystalline character. Density distribution analysis indicated PVA molecular chains are more easily adsorbed on the SiO2 surface than PVP molecular chains. Finally, an analysis of binding energies and pair correlation functions of interfacial interaction models revealed the interaction mechanism of nano-SiO2 particles in PVA/PVP systems. Hydrogen bond interactions between polar functional groups in polymer molecular chains and the hydroxyl groups of the SiO2 surface are involved in adsorption of the polymers on the SiO2 surface and explain why nano-SiO2 particles can significantly influence the properties of PVA/PVP systems.

The dynamic characteristics of squeeze piezo printhead are studied using reduced frequency model for inks with different viscosity. While piezo inkjet mainly applies in paper printing and graphic output, many new applications have emerged in the last few years. These new applications involve inks with high viscosity. Ink viscosity is a key material parameter in printhead design. In order to take viscous damping into account, reduced frequency model is applied to model the printhead fluid cavity. Squeeze piezo printhead models with different inks (viscosity range from 20 cps to 110 cps) are built using software ANSYS15.0. Meniscus velocity and pressure at the nozzle entrance excited by frequency from 10 KHz to 200 KHz are calculated. Meantime, the velocity and pressure distribution around the first resonant frequency (which is 21250 Hz in the paper) are also calculated. The results reveal that both meniscus velocity and pressure decrease with increasing viscosity. It is notable that ink viscosity affects the printhead dynamic response significantly near resonant frequency. When the exciting frequency is far from resonant frequency, the influence of viscosity is small. The reduced frequency model is a powerful tool for the design optimization of the piezo printhead.

In 3DP fabricating artificial bone scaffolds process, the interaction mechanism between binder and bioceramics power determines the microstructure and macro mechanical properties of Hydroxyapatite (HA) bone scaffold. In this study, we applied Molecular Dynamics (MD) methods to investigating the bonding mechanism and essence of binders on the HA crystallographic planes for 3DP fabrication bone scaffolds. The cohesive energy densities of binders and the binding energies, PCFs g(r), mechanical properties of binder/HA interaction models were analyzed through the MD simulation. Additionally, we prepared the HA bone scaffold specimens with different glues by 3DP additive manufacturing, and tested their mechanical properties by the electronic universal testing machine. The simulation results revealed that the relationship of the binding energies between binders and HA surface is consistent with the cohesive energy densities of binders, which is PAM/HA>PVA/HA>PVP/HA. The PCFs g(r) indicated that their interfacial interactions mainly attribute to the ionic bonds and hydrogen bonds which formed between the polar atoms, functional groups in binder polymer and the Ca, –OH in HA. The results of mechanical experiments verified the relationship of Young׳s modulus for three interaction models in simulation, which is PVA/HA>PAM/HA>PVP/HA. But the trend of compressive strength is PAM/HA>PVA/HA>PVP/HA, this is consistent with the binding energies of simulation. Therefore, the Young׳s modulus of bone scaffolds are limited by the Young׳s modulus of binders, and the compressive strength is mainly decided by the viscosity of binder. Finally, the major reasons for differences in mechanical properties between simulation and experiment were found, the space among HA pellets and the incomplete infiltration of glue were the main reasons influencing the mechanical properties of 3DP fabrication HA bone scaffolds. These results provide useful information in choosing binder for 3DP fabrication bone scaffolds and understanding the interaction mechanism between binder and HA bioceramics power.

To investigate the effects of composition ratios on the properties of PVA/PVP blend membrane, five models of blend membrane with the composition ratios of 4/0, 3/1, 2/2, 1/3, and 0/4 were constructed and simulated using the molecular dynamics simulation. The solubility parameters, mechanical properties, binding energy, pair correlation function, free volume and diffusion of H2O molecules were studied, respectively. Results show that PVA has a good compatibility with PVP, the engineering modulus and binding energy decrease with the addition of PVP content. The diffusion of H2O molecule and fractional free volume increase with the addition of PVP content, the bigger the fractional free volume, the better the diffusion ability for H2O molecules in system. Additionally, the pair correlation functions indicate that the hydrogen bonds are more likely to be formed between H2O molecules and polar functional groups, with the increase of PVP content. This is due to the polarity effect of amide groups (NCO) in PVP is stronger than that of hydroxyl groups (OH) in PVA. A stronger polarity effect can make the hydrogen bonds more easily to be formed between polar groups and water molecules, and this is why the hydrophilicity of membrane increases with the addition of PVP.

为了从微观分子相互作用层面研究三维打印骨支架工艺中的粉末粘结机理及本质,本文采用分子动力学的模拟仿真方法,分别从内聚能密度结合能、对关联函数、力学性能等方面对目前应用较多的PVP、PAM、PVA三种粘结剂的性能进行了研究,并将所得结果进行了分析和比较.仿真结果表明,三种粘结剂与HA相互作用模型的界面结合能的大小关系与粘结剂本身的内聚能密度大小关系一致,即PAM＞ PVA＞ PVP;粘结剂高分子与羟基磷灰石(Hydroxyapatite,HA)的对关联函数分析表明,粘结剂与HA发生相互作用主要是通过高聚物中的极性官能基团与HA中的Ca原子、羟基发生作用形成离子键、氢键,且离子键作用强度较大;此外,三种相互作用模型各个方向的力学性能较单一HA有所降低,且相互作用模型力学性能的优劣关系为PVA/HA＞ PAM/HA＞PVP/HA,这一结论与结合能的大小关系并不完全一致,这说明相互作用模型的力学性能与粘结剂的粘性并不存在特定的内在关系.

During the technology process of 3DP fabrication bone scaffolds, the property of binder is a key factor which affects the quality of bone scaffold. In this research, three models of polymer binders were constructed and simulated by a molecular dynamics simulation method. Some properties (such as density, cohesive energy and mechanical properties) of polymer binders PVP, PAM and PVA were investigated at molecular level. The properties of three binders were also compared, and their inner relations were revealed. Therefore, this study not only forecasts the basic properties of the commonly used polymer binders, but also provides the theoretical basis for the choice of binder in technology process of 3DP fabrication bone scaffolds.

In the three-dimensional directly fabricating hydroxyapatite composite artificial bone scaffold process, the liquid bio-binder is sprayed on the surface of bioceramics powder layer. The spraying volume and the powder size directly influence the mechanical properties of the bone scaffold and the future biodegradation performance. When the size of powder is stable, the amount of binder spraying will directly affect the mechanical strength of bone scaffold. In order to figure out the solidification mechanism of α- n -butyl cyanoacrylate (NBCA) bio-binder on the hydroxyapatite (HA) powder layer, the molecular dynamics simulation method is applied to investigate the binding energy shifts between NBCA on HA crystallographic planes. The mechanical properties can be deduced from this methodology; furthermore, the Knoop identification experiments are used to investigate the effective elastic modules of pure HA system and HA/NBCA composite model. Both the simulation and the experiments results elucidate that HA (110) has the highest binding energy with NBCA as the high planar atom density and the mechanical properties of HA/NBCA mixed system are stronger than the pure HA system on three-dimensional crystallographic; in this sense, the bone scaffolds with different strengths could be fabricated by controlling various NBCA binders liquid doses on the surface of HA powder layers during the 3D printing process.

The theoretical method of molecular dynamics was applied to study the PAM/PVA blends at the level of microscopic molecular interaction.The interaction mechanism and nature of PAM/PVA blends are elaborated from the aspects of the compatibility,binding energy and the correlation function analysis,respectively.We have analyzed the static mechanics of system with different quality components,and studied the effects of dif-ferent quality components on the mechanical properties of system.Results show that the compatibility between PAM and PVA was very good,and the binding energy between the single component of system is decreased with the increase of PVA content,the main reason is that the number of polar functional groups contained in a PAM chain was higher than the same quality PVA chain.In addition,the analysis of the correlation function shows that the single component interacts with each other mainly by hydrogen bonds,and the possibility rela-tionship of the hydrogen bond which formed between the amine groups (—NH 2 ),carbonyl groups (—C ??O), hydroxyl groups (—OH)and the hydrogen atoms around them was O (-C=O)>O (-OH)>N(-NH2 ).This was a re-flection of the polarity relationship among the amide groups,carbonyl groups and hydroxyl groups.The static mechanical results of models with different component quality ratio show that,with the increase of PVA con-tent,the elastic coefficient,the various engineering modulus and cauchy pressure value are all increased,name-ly the increase of PVA content can significantly improve the mechanical properties and ductility of PAM.

An investigation of the molecular interaction within a hydrogel system was conducted using molecular dynamics simulation, and the interaction mechanism of a polyacrylamide/polyvinyl alcohol (PAM/PVA) hydrogel system was examined specifically at the molecular level. Several characteristics of the PAM/PVA composite hydrogel system that are largely dependent on water content and temperature were studied in this paper, such as cohesive energy density, binding energy, mechanical properties and pair correlation function. The cohesive energy density and binding energy of the hydrogel system increased with higher water content. Results also showed that increased temperatures led to a decrease in the cohesive energy density of the system, while binding energy remained unchanged. The mechanical properties of the system were evaluated by analyzing the static mechanic performance. Results showed that elastic coefficients, engineering modulus and ductility decreased with increasing water content and temperature. In addition, analysis of the pair correlation function revealed mainly hydrogen bonding interactions between H2O molecules and surrounding atoms or functional groups. Results also indicated that the strength of these hydrogen bonds was O-water > O-PVA > O-PAM > N-PAM, confirming both the potential and the difficulty of hydrogen bond formation. The aforementioned findings help in understanding the interaction mechanisms between the components of a hydrogel system and in demonstrating the effects of water content and temperature on the PAM/PVA hydrogel system, which provides useful information on the possible operating windows of a biomedical hydrogel-making process.

The combination of hydroxyapatite composite powder and three-dimensional (3D) printing rapid prototyping techniques has markedly improved skeletal interactions in orthopedic surgery applications. 3D printing methodology ensures effective bionic microstructure and shape interactions between an implant and the surrounding normal tissue. In effort to enhance the quality, precision, and mechanical properties of printed bone scaffolds, this study examines binder droplet spreading performance on the surface of hydroxyapatite (HA) microspheres. The piezoelectric nozzle diameter is about 10 μm, which sprays droplets 20 μm in diameter. The average size of HA powder particles is about 60 μm in diameter. Most laboratories, however, are limited to observation of a single droplet 20 μm or smaller in diameter impacting a spherical surface 60 μm in diameter. Based on non-dimensional scale similarity theory in axisymmetric Stokes flow dynamics, this study conducted experiments and simulation on the same collision conditions (droplet 200 μm in diameter, spherical surface 600 μm in diameter). Simulation results were consistent with experiment data, and form a basis for future research on modeling droplet impact on spherical surfaces.

To study interpenetrating network hydrogel system of PAM/PVA, molecular dynamics simulation is made to investigate molecular interaction inside a hydrogel system. Effects of water content on PAM/PVA composite hydrogel performance are studied. It is found that cohesive energy density and binding energy of hydrogel system increase with water content increasing. Meanwhile elastic coefficients, engineering modulus and ductility decreased with increasing of water content. In addition, with analysis of pair correlation function, we found that there are mainly hydrogen bonding interactions between H2 O molecules and surrounding atoms or functional groups. Strengths of hydrogen bonds formed are Owater >OPVA >OPAM >NPAM, which consists with possibility (difficulty) of forming hydrogen bond.

Before performing bone surgery, a diagnosis is obtained mainly based on CT digital images. It is impossible for surgeons to test their operation plans and recovery strategy before surgery. Choosing between strength-match bone nails and bone plates is difficult, and post-operative stress complication is inevitable. Surgeons need to measure defect areas carefully in order to choose appropriate internal fixation devices based only on experience. Consequently, surgery time increases. Longer surgery time means a higher possibility for vein thrombosis or even artery thrombosis. In addition, for caput femoris, which contains many vessels and nerves, a long surgery is more likely to cause intraoperative complications, disability, or even death. A 3DP customized bone preoperative diagnosis model can characterize a given fracture or defect precisely, and thus increase the observation field of view before surgery. This paper first analyze the model structure of skeletal anatomy, and then study the skeletal bionics design of the internal micro structure, the preoperative diagnosis outline shape structure, and the biomechanical property. Based on this study, we fabricate different strength bone scaffold by controlling the 3DP processing parameters, materials size and their shape. The preoperative diagnosis model can help surgeons define the level and type of bone defects. It facilitates choosing between bone nails and bone plates. The preoperative model can also be used as basis to set up bone nails, bone plates, and bone substitute implanting plans. As a physical model for preoperative design, recovery simulation, implant choice, and 3D spatial data measurements, the 3DP preoperative diagnosis model can substantially improve the effect of surgery, decrease surgery time, and consequently, decrease the possibility of intraoperative and post-operative complications.